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Bastawrous M, Ghosh Biswas R, Soong R, Jouda M, MacKinnon N, Mager D, Korvink JG, Simpson AJ. Lenz Lenses in a Cryoprobe: Boosting NMR Sensitivity Toward Environmental Monitoring of Mass-Limited Samples. Anal Chem 2023; 95:1327-1334. [PMID: 36576271 DOI: 10.1021/acs.analchem.2c04203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is commonly employed in a wide range of metabolomic research. Unfortunately, due to its relatively low sensitivity, smaller samples become challenging to study by NMR. Cryoprobes can be used to increase sensitivity by cooling the coil and preamplifier, offering sensitivity improvements of ∼3 to 4x. Alternatively, microcoils can be used to increase mass sensitivity by improving sample filling and proximity, along with decreased electrical resistance. Unfortunately, combining the two approaches is not just technically challenging, but as the coil decreases, so does its thermal fingerprint, reducing the advantage of cryogenic cooling. Here, an alternative solution is proposed in the form of a Lenz lens inside a cryoprobe. Rather than replacing the detection coil, Lenz lenses allow the B1 field from a larger coil to be refocused onto a much smaller sample area. In turn, the stronger B1 field at the sample provides strong coupling to the cryocoil, improving the signal. By combining a 530 I.D. Lenz lens with a cryoprobe, sensitivity was further improved by 2.8x and 3.5x for 1H and 13C, respectively, over the cryoprobe alone for small samples. Additionally, the broadband nature of the Lenz lenses allowed multiple nuclei to be studied and heteronuclear two-dimensional (2D) NMR approaches to be employed. The sensitivity improvements and 2D capabilities are demonstrated on 430 nL of hemolymph and eight eggs (∼350 μm O.D.) from the model organismDaphnia magna. In summary, combining Lenz lenses with cryoprobes offers a relatively simple approach to boost sensitivity for tiny samples while retaining cryoprobe advantages.
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Affiliation(s)
- Monica Bastawrous
- Environmental NMR Center, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Rajshree Ghosh Biswas
- Environmental NMR Center, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Ronald Soong
- Environmental NMR Center, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Mazin Jouda
- Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Neil MacKinnon
- Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Dario Mager
- Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Jan G Korvink
- Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Andre J Simpson
- Environmental NMR Center, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
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Davoodi H, Jouda M, Korvink JG, MacKinnon N, Badilita V. Broadband and multi-resonant sensors for NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 112-113:34-54. [PMID: 31481158 DOI: 10.1016/j.pnmrs.2019.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/08/2019] [Accepted: 05/08/2019] [Indexed: 06/10/2023]
Abstract
It has always been of considerable interest to study the nuclear magnetic resonance response of multiple nuclei simultaneously, whether these signals arise from internuclear couplings within the same molecule, or from uncoupled nuclei within sample mixtures. The literature contains numerous uncorrelated reports on techniques employed to achieve multi-nuclear NMR detection. This paper consolidates the subset of techniques in which single coil detectors are utilized, and highlights the strengths and weaknesses of each approach, at the same time pointing the way towards future developments in the field of multi-nuclear NMR. We compare the different multi-nuclear NMR techniques in terms of performance, and present a guide to NMR probe designers towards application-based optimum design. We also review the applicability of micro-coils in the context of multi-nuclear methods. Micro-coils benefit from compact geometries and exhibit lower impedance, which provide new opportunities and challenges for the NMR probe designer.
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Affiliation(s)
- Hossein Davoodi
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany
| | - Mazin Jouda
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany
| | - Jan G Korvink
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany.
| | - Neil MacKinnon
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany
| | - Vlad Badilita
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Baden-Württemberg, Germany.
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